Process of preparing comminuted cork



Aug. 2, 1932. s. c. BOND 1,870,166

PROCESS OF PREPARING COMMINUTED CORK Filed Jan. 22, 1950 r0 l/YDE s 575APatented Aug. 2, 1932 UNITED STATES PATENT OFFICE SAMUEL C. BOND, OFHOLLY OAK, DELAWARE, ASSIGNOR TO THE HENRY P. SCOTT COM- PANY, ACORPORATION OF DELAWARE, .AS TRUSTEE PROCESS OF PREPARING COMMINUTEDCORK Application filed January 22, 1930. Serial No. 422,665;

My invention relates to an improved process of preparing comminutedcork.

The main object of my invention is to provide an improved process ofpreparing comminuted cork, which results in the comminuted cork having auniform low moisture content. This low and uniform moisture content'isvery desirable in the manufacture of articles of molded comminuted cork,to reduce subsequent shrinkage of such articles. A further object of myinvention is to provide an improved process for preparing comminutedcork, which results in a moreefficient separation of the ground corkfrom the exli traneous matter, or hard material, contained in the wastecork used as the raw material in this process. A further object of myinvention is to provide a process for preparing comminuted cork. inwhich the particles of cork material are toughened before comminution soas to put them in abetter condition for subse uent treatment.

urther objects, and objects relating to details and economies ofoperation, will definitely appear from the detailed description tofollow. In one instance, I accomplish the objects of my invention by themeans described in the following specification. My invention is clearlydefined and pointed out in the appended claims. The single figure of theaccompanying drawing, forming a oart of this specification, illustratesdiagrammatically an apparatus by which my invention may be carried out.

Heretofore, it has been the practice to prepare comminuted or groundcork from waste cork, or cork material, by subjecting this raw materialto successive cutting and grinding operations, reducing the particles tothe desired size, and to a separating action by which the hard materialof extraneous matter contained in the raw material is removed. The wastecork constituting the raw material contains more or less hard material,known as hard back which must be separated from the cork. After thematerial has been ground this can be accomplished by centrifugalseparators, since the hard material is brittle and 50 is ground to adust which is readily separated from the lighter and larger particles ofcork.

However, the waste cork frequently contains a good deal of moisture,which it is desirable to remove as completely as possible, so that theground cork may have a uniform low moisture content. It has been thepractice, heretofore, to dry the waste cork by a blast of hot air, butthis has resulted in baking the surface of the cork, making it brittleso that some of the cork islost in the separation process. being removedwith the hard material.

In general. my invention consists in subjecting particles of the corkmaterial to the action of an atmosphere of steam which is at atemperature above the boiling point of water at atmospheric pressure,and subsequently subjecting these particles to the grinding operation. Ipropose to treat the waste cork, so as to form particles ofsubstantially uniform size, and these particles are then conveyed to astorage bin into which live steam is conducted. This steam iscontinuously withdrawn from the bin by a suitable exhaust fan, whichreduces the pressure in the bin slightly below atmospheric pressure. Thesteamed and. thus heatedparticles are then led off through a measuringdevice, which prevents the escape of steam from the storage bin to thegrinders in which the cork is reduced to particles of the desired sizeand the hard material is separated, any excess I moisture remaining inthe cork being liberated during and directly after the grindingoperation. The steam within the bin may be superheated or saturated, butshould have super-heat at the time of original contact with thematerial, and for the sake of economy should be saturated at the time ofleaving the material being dried. Having displaced all water, air orother volatile liquids. the weight or amount of the remaining water isequal to the weight of the equivalent number of cubic feet of steam intheabove mentioned steam atmosphere, and can be readily determined fromtables giving the properties of steam. I

Referringto the accompanying drawing, which illustrates diagrammaticallyan arrangement of apparatus for carrying out my lmproved process, wastecork 1s fed into the v 12 having a hopper bottom 13.

breakers in which it is reduced to particles of substantially uniformsize, such as will pass through a screen having a three-quare ter inchmesh. These breakers operate by cuttingaction, with as little crushingas possible, and are well known in the art. From the breakers, theparticles of cork are conveyed by pipe'll to a covered storage bin Thedischarge outlet for the particles of cork material is at the bottom ofthis bin and a rotating measuring device l l delivers the particles intothe pipe by which they are conveyed to the grinders for the subsequentgrinding and separating operations. This measuring device 14 acts as aseal for the bottom of the bin preventing the escape of steam into thepipe 15. Live steam under pressure above atmospheric is led into thelower part of the bin through the pipe 16 and acts upon the particles ofcork in said bin. An exhaust pipe 17, communicating withthe inlet of anexhaust fan 18 is connected to the upper part of the bin so as to drawthe steam continuously from the bin and discharge it through the pipe19. The saturated steam under pressure injected into the bin throughpipe 15 immediately becomes superheated because its pressure is reducedto atmospheric pressure or slightly below. The excess heat in thissuperheated steam vaporizes the moisture contained in the cork. thiscase it is desired to have the cork substantially bone dry. Therefore,the point of cork discharge is adjacent to the steam inlet, and at thesame time, the cork is as dry as the steam and so hot that the littlewater present as steam is evaporated after assing the measuringdevice.will be noted that the drier cork is in contact with the dry steam andthe wet cork with the wet steam.

The result oi subjecting the particles of cork to the action or steambefore grinding them is to toughen the cork, so as to make it more softand resilient and put it in a better condition for the subsequentgrinding operation. The steam acts on the cork, and not on the particlesof hard material carried by the Waste cork, and, consequently, a moreefficient separation of the cork from the hard material is secured. lhave found in practice that I secure approximately ten per cent greateryield of cork where this'process is used, and I believe this to be dueto the fact that none of the cork is -n1a le brittle and crushed to dustwith the hard material. Furthermore, the steam acts to eliminate theexcess moisture in the cork, with theresult that the particles of corkhave a uniform low moisture content. This is very desirable becauseitreduces the amount of shrinkage in the articles molded from thiscomminuted cork.

I am aware that the method herein described may be chan ed considerablywithout departing from t e spirit of my invention and, therefore, Iclaim my invention broadly as indicated by the appended claims.

What I claim is:

1. The process of refining crude cork having resilient and non-resilientcomponents, which comprises subjecting the crude cork to an atmosphereof hot water vapor to toughen the resilient portions thereof, grindingthe thus treated cork to effect granulation of the resilient portionsand pulverization of the non-resilient portions, and separating thegranulated resilient material from the pulverized material.

2. The process of refining crude cork having resilient and non-resilientcomponents and an excessive moisture content, which comprises breakingup the crude cork into small pieces of substantially uniform size,passing superheated steam into intimate contact with said pieceseflecting heating of said pieces and toughening of the resilientportions thereof, grinding said pieces while still hot to granulate theresilient portions and pulverize the non-resilient portions and therebyallowing the granulated resilient portions to release entrappedmoisture, and separating the granulated resilient cork from thepulverized non-resilient material.

SAMUEL G. BOND.

